The board and move logic came out fine, grid with a column-stack approach, nothing too tricky.
Start by clarifying requirements and constraints, then design a clean object-oriented model for the board and game logic. Implement move logic and winner detection efficiently, analyze time and space complexity, and finally discuss extensions like AI and scalable multiplayer with trade-offs.
Pro tip: Demonstrate awareness of production concerns by mentioning how you'd test the winner detection and handle edge cases like a full board or invalid moves. Also, when discussing AI, briefly compare minimax with alpha-beta pruning versus a simpler heuristic to show you understand trade-offs.
Ask about board size, win condition, input format, and whether it's for a single machine or distributed. Confirm assumptions like standard 7x6 board and four-in-a-row win.
Propose a Board class with a 2D array or list of columns, and methods for dropping a piece, checking valid moves, and detecting a win. Explain how to track the last move to optimize winner detection.
State that move logic is O(1) if using column heights, and winner detection is O(1) by checking only lines through the last move. Space is O(rows*cols). Mention potential optimizations like bitboards.
Outline how to add an AI using minimax with alpha-beta pruning, heuristic evaluation, and iterative deepening. Mention time complexity and how to limit search depth for responsiveness.
Describe a client-server architecture with WebSockets for real-time play, a game service for matchmaking and state management, and a database for persistence. Discuss scaling via sharding, caching, and handling concurrency.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.